Evaluation of biological control potential of locally isolated antagonist fungi against Fusarium oxysporum under in vitro and pot conditions

Fusarium oxysporum f sp. phaseoli is responsible for wilt disease of Phaseolus vulgaris L., which results in extensive damage to the crop. Biological control of soil borne plant pathogens is a potential alternative to the use of environment harming chemical pesticides. Therefore, the study was undertaken to determine the potential of locally isolated antagonist fungi (Aspergillus niger, Penicillium citrinum, Trichoderma harzianum, and Trichoderma viride) to manage fusarium wilt of common bean. Under in vitro condition all antagonist species had inhibited the radial growth of pathogen; however in the case of A. niger this inhibition was insignificant. The maximum mycelial growth of all antagonists was recorded at 25 C and decreased above this temperature. Under pot conditions, all treatments were able to boost plant growth and provide significant reductions in disease levels. The highest plant growth and chlorophyll a+b content were observed in plants treated with T. harzianum, followed by T. viride, P. citrinum and A. niger. The effect of these treatments on fusarium wilt was found to be inversely proportional to the plant growth. Maximum control of wilt disease was observed in bean plants treated with T. harzianum (71.4%). Effectiveness of the other antagonists was recorded in the following order: T. viride (67.8%), P. citrinum (53.5%) and A. niger (35.7%).